“First Blood” is a frightening movie. It shows what war can do to its heroes, indicting us as a people for producing men so adept at killing they can do nothing else. It also gives a worst-case scenario in the escalating nightmare that narrow-mindedness and bigotry can cause.

It also, of course, features a very cool guy doing some very cool things with knives and guns and stuff. That’s all the copycat filmmakers seem to remember these days; they would do well to watch “First Blood” again and see all those OTHER things that are in there, too.

John Rambo (Sylvester Stallone in his first successful non-Rocky role) is a Vietnam veteran passing through town somewhere in the American northwest. The local sheriff (Brian Dennehy) doesn’t like the looks of him: He could use a shower and a haircut, and we don’t take kindly to drifters in these parts anyway, thank you. Since he rules his podunk little town with an iron fist, he hauls Rambo in for “vagrancy.”

Soon the other cops are picking on Rambo, too, and soon he’s beating the crap out of them and escaping into the forest. They’ve drawn first blood, so he feels justified in retaliating, which just makes them angrier, so THEY retaliate, too, and it goes back and forth from there. (See the war metaphor?)

The first scenes in the forest are scary and tense, as Rambo turns the landscape into a horrible maze of booby-traps and ambushes. Unwilling to admit they’ve been defeated by a lone man, the cops call in military backup. But Rambo is a one-man wrecking crew, as they say, and it’s going to take more than guns to stop him.

Then arrives Col. Trautman (Richard Crenna), Rambo’s commanding officer from the war. It was he who trained Rambo to be the survivalist he is now, able to live off the land and “eat things that would make a billy goat puke,” as Trautman puts it. He’s not here to save Rambo from the cops, though; he’s here to save the cops from Rambo.

OK, it’s all very exaggerated in a way that will appeal to men and other children, but Stallone really does give a haunting performance. The final few minutes, especially, show great range from the actor, and provide the film with its resonating depth and thought-provoking morality.

It’s a shame this film became a prototype of sorts for shoot-’em-up, one-man-against-the-world action flicks, because it’s so much better than that. It’s undeniably entertaining on that level, too, but it has more to offer than just a high body count. It’s one of the best movies ever to operate wholly on the level of a bad dream: The instigating factors are not plausible, but what if you DID find yourself in Rambo’s situation, where victory seems more and more hopeless?

This is a dark drama about war and the exorcising of demons, and an unforgettable one at that.